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ABSTRACTFew data on the molecular characteristics and epidemiology of Staphylococcus aureusfrom Indonesia are available. The purpose of the present study was to define S. aureusreservoirs in both the Indonesian community and hospital using a collection of 329 nasal carriage isolates obtained during a survey of 3,995 healthy individuals and patients from Java, Indonesia. Only one strain (0.3%) was identified as methicillin-resistant S. aureusby mecAgene PCR. The Panton-Valentine leukocidin (PVL) genes were detected in 35 methicillin-sensitive S. aureusstrains (10.6%). Molecular typing by pulsed-field gel electrophoresis of the 329 isolates showed extensive genetic diversity among both PVL-positive and PVL-negative strains. In Surabaya, Indonesia, however, a cluster was identified that was strongly associated with the presence of the PVL locus (P< 0.0001). As determined by high-throughput amplified fragment length polymorphism, PVL-positive strains occurred throughout all major AFLP clusters (I to IV). Multilocus sequence typing of a subset of isolates showed that most PVL-positive strains belonged to sequence type (ST) 188, while most PVL-negative isolates belonged to ST45. The high prevalence of PVL-positive S. aureusstrains in certain regions of Indonesia is of concern since these strains may cause severe infections in the community and in hospitals.

ABSTRACTThe epidemiology and risks of Staphylococcus aureuscarriage in continuous peritoneal dialysis (CPD) patients was studied in a single tertiary-care institution. On outpatient visits samples for culture were routinely taken prospectively from the CPD catheter exit site and the vestibulum nasi. Seventy-five patients with at least one culture positive for S. aureusin this period were included: 43 had genotypically identical S. aureusstrains in over 80% of the cultures and were classified as persistent carriers; 32 were intermittent carriers. Persistent carriage was associated with a threefold higher risk for CPD-related infections and sixfold higher rates of vancomycin consumption compared to those for the intermittent carriers. No methicillin or vancomycin resistance was detected.

Clinical isolates of Staphylococcus aureus (n = 276) were collected in 10 different hospitals located in the Southwest (cities of Ibadan and Lagos) and North-Central (city of Jos) parts of Nigeria. Resistance profiling of these strains revealed that the vast majority was still susceptible to methicillin (98.6% MSSA). Pulsed field gel electrophoresis (PFGE) performed for these strains identified 45 different genotypes, nine of which were identified in four or more different hospitals. The major PFGE type (genotype 2) comprised 23% of all isolates. In addition, several other strains were shown to be endemic in individual hospitals. Three out of four multi-resistant MRSA strains that were detected were sequence type 8 (ST8) as determined by array-based multi-locus sequence typing (MLST). PCRs for cataloguing the staphylococcal cassette chromosome (SCCmec) type were negative for two of these, suggesting the existence of a new methicillin-resistance gene complex in the ST8 genetic background. In conclusion, major clones of MSSA circulate in Nigeria, and the MRSA incidence is still low. However, the occurrence of old and new versions of SCCmec in some of the ecologically abundant MSSA strains should be taken as a serious warning since clonal expansion of this type of strains is not unprecedented.

ABSTRACTA newly developed oligonucleotide array suited for multilocus sequence typing (MLST) of Staphylococcus aureusstrains was analyzed with two strain collections in a two-center study. MLST allele identification for the first strain collection fully agreed with conventional strain typing. Analysis of strains from the second collection revealed that chip-defined MLST was concordant with conventional MLST. Array-mediated MLST data were reproducible, exchangeable, and epidemiologically concordant.

ABSTRACTNonbullous impetigo is a common skin infection in children and is frequently caused by Staphylococcus aureus. Staphylococcal toxins and especially exfoliative toxin A are known mediators of bullous impetigo in children. It is not known whether this is also true for nonbullous impetigo. We set out to analyze clonality among clinical isolates of S. aureusfrom children with nonbullous impetigo living in a restricted geographical area in The Netherlands. We investigated whether staphylococcal nasal carriage and the nature of the staphylococcal strains were associated with the severity and course of impetigo. Bacterial isolates were obtained from the noses and wounds of children suffering from impetigo. Strains were genetically characterized by pulsed-field gel electrophoresis-mediated typing and binary typing, which was also used to assess toxin gene content. In addition, a detailed clinical questionnaire was filled in by each of the participating patients. Staphylococcal nasal carriage seems to predispose the patients to the development of impetigo, and 34% of infections diagnosed in the Rotterdam area are caused by one clonal type of S. aureus. The S. aureusstrains harbor the exfoliative toxin B (ETB) gene as a specific virulence factor. In particular, the numbers (P= 0.002) and sizes (P< 0.001) of the lesions were increased in patients infected with an ETB-positive strain. Additional predictors of disease severity and development could be identified. The presence of a staphylococcal plasmid encoding multiple antibiotic resistance traits, as detected by binary typing, was associated with a reduction in the cure rate. Our results recognize that a combination of staphylococcal virulence and resistance genes rather than a single gene determines the development and course of nonbullous impetigo. The identification of these microbial genetic markers, which are predictive of the severity and the course of the disease, will facilitate guided individualized antimicrobial therapy in the future.

Staphylococcus aureusextracellular DNA (eDNA) plays a crucial role in the structural stability of biofilms during bacterial colonization; on the contrary, host immune responses can be induced by bacterial eDNA. Previously, we observed production of S. aureusthermonuclease during the early stages of biofilm formation in a mammalian cell culture medium.

Immune modulators are known to be produced by matured biofilms and during different stages of planktonic growth of Staphylococcus aureus. Little is known about immune modulator production during the early stages of biofilm formation, thus raising the following question: how does S. aureusprotect itself from the innate immune responses at these stages? Therefore, we determined the production of the following immune modulators: chemotaxis inhibitory protein of staphylococci (CHIPS); staphylococcal complement inhibitor (SCIN); formyl peptide receptor-like 1 inhibitor; gamma-hemolysin component B; leukocidins D, E, and S; staphylococcal superantigen-like proteins 1, 3, 5, and 9; and staphylococcal enterotoxin A.